Sound-wave transmitting and amplifying device



July 17, 1928. 1,677,632

w. HARDEN SOUND WAVE TRANSMITTING AND AMPLIFYING DEVICE Filed March 21, 1927 5957 .58 32 izgwlll I N VEN TOR.

4 k! I 4 7 Warm Hrmonr A TTORNEY Patented July 17, 1928.

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WALTER HARDEN, OF CINCINNATI, OHIO.

SOUND-WAVE TRANSMITTING AND AMPLIFYING DEVICE.

Application filed March 21, 1927. Serial No. 176,863

The invention relates to means particularly, although not exclusively, adapted to reproduce'and amplify the volume of the sound waves produced by stringed musical instruments.

The objects of the invention are to provide simple and efficient means adapted to transmit and amplify sound waves and vibrations of a body; and to provide convenient, economical and efiicient means to attach the sound wave amplifier and the vibration transmitter to said body.

The invention consists in the combination of the elements, the arrangement of the parts, and in the details of the construction, as hereinafter specified and claimed.

, In the drawings:

, Fig. 1 is a plan view of a musical instrument having the invention attached thereto, and with parts broken away;

Fig. 2 is a section of parts taken on a line corresponding to 2-2 in Fig. 1, and showing a section of the support on a line corresponding to 2-2 in Fig. 4;

Fig. 3 is a plan view of the transmitter and vibration conductor, with parts broken away;

Fig. 4 1s a perspective view of the support;

Fig. 5 is a diagrammatical new of the amplifying circuit; and

Fig. 6 1s a vertical section, with parts broken away, taken on a line corresponding to 2-2 in Fig. 1, showing a modified construction.

The preferred construction of the invention is exemplified on usual musical instrument or uitar 1, the body 2 of which has sounding board 3, and sound-hole 4, as usual, in top 5. Above the sounding-board and the sound-hole are strings 6 spaced from the top of the body, as usual, by bridge 7, suitably fixed to the top of the guitar.

The U-shape support 8 has-its upper leg 8' protruding from within the guitar and engages felt, rubber or other matenal, v1- bration insulator strip 9 which engages the outer side 10 of top 5 of the guitar.

The link 11, integral with leg 8', of the U- shape support, extends at' right angles to leg 8' and inwardly of the guitar.-

The arm 12 is pivotally connected, by pin 13, to side edge 14 of link 11 and normally extends parallel with the leg 8 of the U-shape support. The end 15 of the arm 12 is inclined upwardly and outwardly and is adapted to engage felt, rubber or other material, vibrationv insulator 16 which engages the lower edge of usual rib or brace 17 fixed to the inner side 18 of top 5 of the guitar. Suitably secured to the upper end of link 11, and spaced from arm 12, is lug 19, extending at right angles to the link and having hole 20 in its end 21. The thumb screw 22 is threaded in the hole 20 in lug 19. Manually screwing the thumb screw inwardly is adapted to contact its inner end 23 with end 24 of arm 12, whereby end 15 of the arm is forced upwardly in close engagement with insulator 16, thereby engagin the insulator with the lower edge of rib 1 and the leg 8 of U- shape support 8 is forced in close engagement with insulator 9 which is forced in close engagement with top 5, whereby the U-shape support is securely fixed to the guitar and is efi'ectually insulated from vibrations of body 2 and sounding board 3.

llntegrally connected with the lower end 25 of link 11, and extending parallel with leg 8, is leg 25' having transmitter or micro phone 26 secured adjacent its upper side 27, as by screw 28. The screw 28 may be formed from vibration insulator material and an insulator (not shown) may be insulated between leg 25 and transmitter 26 to prevent vibration being transmitted .from U-shape support 8 to the transmitter.

The transmitter 26 may be of any suitable construction to facilitate in clearly and effectually reproducing the tones of the guitar 1, b methods hereinafter explained.

The transmitter 26, may consist of casing 29 having therein .a magnet (not shown), having wound thereabout a coil (not shown), the ends of which are connected with conductors 30 and 31 which enter the casing, through hole 32.

The usual diaphragm 33, of transmitter 26, has secured thereto in any suitable manner, as by welting, the nut 34 having end 35, of rod or vibration conductor 36 threaded thereto.

The upper bent end 37, of rod- 36, protrudes through hole 38 in top 5, of body 2 of guitar 1, and is securely fixed to the outer side 10, of top 5, as by screw 39, whereby the sound vibrations of sounding board 3,

produced b strings 6, are communicated, through re 36, to diaphragm 33 of transmitter 26.

For the purpose of reproducing and amplifying the tones of strings 6 of the guitar,

in the musical instrument any suitable device, circuit or arrangement of elements may be utilized.

One form of a usual reproducing and amplifying device is represented by the diagrammatical view shown in Fig. 4, in which conductors 30 and 31, of transmitter 26, are respectively connected with grid 40, of tube 41, and -A terminal 42 of A-battery 42 through the rheostat 43 which is connected with filaments 44 and 45, respectively, of tubes 41 and 46. The plate 47 of tube 4 is connected, through transformer 48, to +13 49 terminal of B-battery 50. And plate 51, of tube 46, is connected, through speaker 52, t0 +B 49 terminal of B-battery 50. The grid 53, of tube 46, is connected, in a usual manner, through transformer 48 to the side of filaments 44 and 45 and also to B terminal 54 of B-battery 49, through +A terminal 55 of battery 42. The resistance 56 connecting conductors 30 and 31 is intended to eliminate undesirable noises from speaker 52.

It is apparent that additional stages of transformer coupled. resistance coupled or other form of amplification may be incorporated in the circuit shown in Fig. 4, when it is desirable to increase the volume of the tones from the guitar.

The transmitter may be positioned with- 1, with the vibration conductor 36 omitted or disconnected from diaphragm 33, whereby the sound waves, produced by strings 6, are conducted by the air from sounding-board 3 to diap ragm 33.

The rod 36 may be connected with various kinds of musical instruments, as horns, drums, or other vibrating bodies.

A11 advantage of the invention is that by means of vibration conductor 36, the vibrations of a body. may be conducted advantageously' for various purposes. As for instance, instead ofutilizing the present method of broadcastin concerts, and other formsof music, by ra io, the vibrations of each musical instrument may be conducted to the microphone by a plurality of conductors 36 connected with the respective instruments and the microphone, microphone can be positioned in a room from which the sound waves produced by the instruments are excluded.

It is apparent that I have invented a practical and highly desirable invention for the purposes intended, and which may be utilized to effect various results. If desirable, only the instruments having low volume in an orchestra may have the invention operatively attached thereto, whereby the efiect of the resultant music may be regulated by increasing or reducing the volume of the tones ofthe respective instruments.

' Moreover, the reproduction or reproduction and amplification of the music produced by 'link and having a.

whereby the a single instrument will effect practically the same results as where two or more instruments are used without amplification of the normal volume of the tones.

In Fig. 6,1 show a modified construction of parts of the invention. Screw 57 has reduced portion 58 rotatably received in hole 59, in top 37, of rod 36. The thread portion 60, of the screw is threaded to bushing 61, suitably fixed inhole 62, of top 5, of body 2, of the musical instrument 1, whereby manual rotation of head 63 of the screw is adopted to raise and lower the'rod 36 for the purpose of controlling the position of disc or diaphragm 33, of transmitter 26, with respect to the usual magnet (not shown), or other similar and suitable mechanism. or material, within casing 29 of the transmitter. I have found that, using the proper adjustment of diaphragm 33 is efiective in eliminating undesirable noises, and improving the tone quality of the amplified sound vibrations produced by strings 6 of the instrument.

Vhile I have chosen to illustrate the forms and constructions of my invention by the herein drawings and explanations of the same. it is understood that the invention resides in the combination, arrangement of the parts and in the details of the construction, as hereinafter claimed. It is further understood that changes in the precise embodiment of the invention, can be made within the scope of what is claimed without departing from the spirit of the invention, as other ex edients may readily suggest themselves to t e art.

' What I claim as new and desire to secure by Letters Patent is:

1. The combination with a strin ed musical instrument having a rib and aving a sounding-board, of a U-shape support comprising 'a link having an upper and a lower leg, an arm pivotally connected with said link, a stud'fixed to the upper end of said as disclosed herein,

hole therein, a thumbscrew. threaded in saidhole and adapted to engage an end of said arm, thereby forcing the other end of said arm in engagement with said rib, thereby maintainm said upper leg in fixed relation adjacent t e top 0 said instrument, whereby said U-shape support is maintained in fixed position with respect to said instrument, a transmitter fixedto said lower leg andhaving 9. diaphragm, a vibration conductor operatively connected with the dia mitter and said soundmg-board, and means connected with said transmitter to reproduce and alnplifv the sound waves produced by the strings of 'said'instrument.

2. The combination with a Stringed musi-' cabinstrument having a sounding board, a

transmitter within said instrument and ha ving a.diaphragm', means connected with said phragm of saidtrans emma transmitter to reproduce and amplify the sound waves produced by the strings of said instrument, means supporting said transmitter comprising a U-shape support consisting of a link having an upper and a lower leg integral with its respective ends, means to clamp said upper leg to said instrument, means to secure said transmitter to said lower leg, and a vibration conductor connecting said diaphragm with said sounding board.

3. The combination with a stringed musical instrument having a sounding board, a transmitter within said instrument and having a diaphragm, means connected with said diaphragm to reproduce the sound waves produced by the strings of said instrument, means supporting said transmitter comprising a U-shape support consisting of a link having an upper and a lower leg integral with its respective ends, means to clamp said upper leg to said instrument, means to secure said transmitter to said lower leg, and

e a vibration conductor connecting said diaphragm with said sounding board.

4. Means for connecting a transmitter with a musical instrument having a rib and a sounding board comprising a U-shape support having an upper and a lower leg integral with its upper and lower ends, respectively, an arm pivotally connected with said link, a stud integral with the upper end of said link and havi a hole therein, and a thumb screw threaed in said hole and adapted to engage an. end of said arm thereby forcing the other end of said arm in engagement with said rib, whereby said upper leg is maintained in fixed relation adjacent the outer side of the top of said instrument and said U-shape support is maintained in fixed position with respect to said sounding board.

5. Means for operatively connecting a microphone to a musical instrument having a rib and having a sounding-board, comprising a support consisting of a link having an upper and a lower leg, an arm pivotally connected with said link, a stud fixed to the upper end of said link and having a hole therein, a thumb-screw threaded in said hole and adapted to engage an end of said arm,

thereby forcing the other end of said arna in engagement with said rib thereby maintaining said upper leg in fixed position adjas cent and insulated from the outer side of the top of said instrument, whereby said support is maintained in fixed position with respect to said sounding-board, and a vibration conductor connected with. the diaphragm of said microphone and said sounding-board.

WALTER :1 EN. 

